On Fri, 2021-04-09 at 16:58 +0200, Toke Høiland-Jørgensen wrote: > Paolo Abeni <pab...@redhat.com> writes: > > > Currently the veth device has the GRO feature bit set, even if > > no GRO aggregation is possible with the default configuration, > > as the veth device does not hook into the GRO engine. > > > > Flipping the GRO feature bit from user-space is a no-op, unless > > XDP is enabled. In such scenario GRO could actually take place, but > > TSO is forced to off on the peer device. > > > > This change allow user-space to really control the GRO feature, with > > no need for an XDP program. > > > > The GRO feature bit is now cleared by default - so that there are no > > user-visible behavior changes with the default configuration. > > > > When the GRO bit is set, the per-queue NAPI instances are initialized > > and registered. On xmit, when napi instances are available, we try > > to use them. > > Am I mistaken in thinking that this also makes XDP redirect into a veth > work without having to load an XDP program on the peer device? That's > been a long-outstanding thing we've been meaning to fix, so that would > be awesome! :)
I have not experimented that, and I admit gross ignorance WRT this argument, but AFAICS the needed bits to get XDP redirect working on veth are the ptr_ring initialization and the napi instance available. With this patch both are in place when GRO is enabled, so I guess XPD redirect should work, too (modulo bugs for untested scenario). Thanks! Paolo
